CarSpecsHQ

245/40R15 vs 185/60R14

185/60R14 is a safe swap for 245/40R15 by the usual ±3% rule: the diameter differs by +0.10%.

15" → 14"
245/40R15 22.72" · 185/60R14 22.74" · drawn to scale

Side by side

245/40R15185/60R14Difference
Overall diameter22.72"22.74"+0.02" (+0.10%)
Section width245 mm185 mm-60 mm
Sidewall3.86"4.37"+0.51"
Rim15"14"-1"
Circumference71.4"71.4"+0.1"
Revs per mile888887-1
Ride height——+0.01"
Speedometer reads 60 mph60.060.1+0.1 mph

Speedometer and odometer

020406080100120 reads 60 · actual 60.1 mph

With 185/60R14 on a car calibrated for 245/40R15, the speedometer reads 59.9 mph when you're really doing 60, and the odometer under-counts by 0.1%.

Speedo showsActual speed
30 mph30.0 mph
45 mph45.0 mph
60 mph60.1 mph
70 mph70.1 mph
80 mph80.1 mph

Other sizes close to 245/40R15

Questions

Can I replace 245/40R15 with 185/60R14?

185/60R14 is a safe swap for 245/40R15 by the usual ±3% rule: the diameter differs by +0.10%.

What's the difference between 245/40R15 and 185/60R14?

185/60R14 is 0.02" taller and 60 mm narrower; the sidewall is +0.51". At an indicated 60 mph you'd actually be doing 60.1 mph.

Will 185/60R14 fit on 245/40R15 wheels?

No — 245/40R15 needs a 15" wheel and 185/60R14 a 14" wheel. This is a plus/minus-size swap that changes wheels too.